Although herbivory and other types of plant damage typically are viewed as detrimental to plant survival and performance, vigorous regrowth, greater seed set, and fitness benefits may be possible when damage to the apical meristem, or actively growing stem terminal, is involved. Such damage releases apical dominance, or the hormonal suppression of lateral buds, activates dormant lateral buds, and enables lateral shoots to grow. Since in plants with terminal flowers, each stem may bear a flower, removal of the apical meristem may result in stem bifurcation and ultimately increase the number of flowers and seeds, thereby increasing potential fitness. In the current study, possible overcompensation in response to apical meristem damage caused by simulated herbivory (clipping) and the gall midge Asphondylia borrichiae Rossi and Strong (Diptera: Cecidomyiidae) (galling) was investigated in the native coastal halophyte, sea oxeye daisy Borrichia frutescens (L.) DC. (Asteraceae), in relation to nutrient supplementation. Results suggest a strong correlation between stem count and gall count at the study site; moreover, apical dominance was relatively weak early in the growing season and stronger in short plants that were shaded by taller neighbors later in the season. Results also indicate that overcompensation or even full compensation is an unlikely response to apical meristem damage in B. frutescens. Stem count was similar across all stem treatments, but increased significantly with nutrient supplementation, which all supports weak apical dominance in sea oxeye daisy. Nearly all measures of fitness also were either slightly or significantly lower when clipped and galled compared to plants with stems intact, while seed count responded positively to nutrient supplementation.
| Identifer | oai:union.ndltd.org:unf.edu/oai:digitalcommons.unf.edu:etd-1506 |
| Date | 01 January 2014 |
| Creators | Rowan, Lisa S. |
| Publisher | UNF Digital Commons |
| Source Sets | University of North Florida |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | UNF Theses and Dissertations |
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